Discrete circuits (or “discretes”) may be used to convey a particular command or status information regarding equipment, components, or devices aboard an aircraft. For example, a landing gear discrete may be used by a fuel controller aboard the aircraft as a basis for determining whether to transfer fuel from a first fuel tank (e.g., a fuel tank located in a fuselage) to a second fuel tank (e.g., a fuel tank located in or near a wing of the aircraft).
A wetting current may be used to clean contacts of a switch included in a discrete in order to maintain and ensure quality connections when, e.g., the switch is closed and current passes through a discrete input circuit. Discrete input circuits may require large wetting currents. For example, an engine control discrete input may require wetting currents on the order of ten milliamps (10 mA) to forty milliamps (40 mA) per discrete. Using conventional techniques, the large wetting currents may require large components to be used in order to safely dissipate the power associated with the current. Aircraft reliability analyses may require even larger components to be used if additional de-rating (e.g., component power dissipation de-rating) is required.